quartz, one of the commonest of all rock-forming minerals and one of the most important constituents of the earth's crust. Chemically, it is silicon dioxide, SiO₂. It occurs in crystals of the hexagonal system, commonly having the form of a six-sided prism terminating in a six-sided pyramid; the crystals are often distorted and twins are common. Quartz may be transparent, translucent, or opaque; it may be colorless or colored. Varieties are classified as crystalline and cryptocrystalline. Crystalline varieties include ordinary colorless crystallized quartz, or rock crystal; rose quartz; yellow quartz, sometimes used as imitation topaz topaz (tō`păz), aluminum silicate mineral with either hydroxyl radicals or fluorine, Al₂SiO₄(F,OH)₂
..... Click the link for more information. ; smoky quartz, or cairngorm stone; milk-white milky quartz; aventurine quartz, which contains scales of hematite or mica; and amethyst amethyst (ăm`əthĭst) [Gr.,=non-drunkenness], variety of quartz , violet to purple in color, used as a gem.
..... Click the link for more information. . Varieties of cryptocrystalline quartz, the crystal structure of which can be seen only under the microscope, if at all, are chalcedony chalcedony (kălsĕd`ənē)
..... Click the link for more information. , flint flint, variety of quartz that commonly occurs in rounded nodules and whose crystal structure is not visible to the naked eye. Flint is dark gray, smoky brown, or black in color; pale gray flint is called chert.
..... Click the link for more information. , hornstone, and chert. Colored varieties of chalcedony known by special names are carnelian carnelian (kärnēl`yən) or cornelian
..... Click the link for more information. , sard, chrysoprase, agate agate (ăg`ĭt), translucent, cryptocrystalline variety of quartz and a subvariety of chalcedony .
..... Click the link for more information. , onyx onyx (ŏn`ĭks), variety of cryptocrystalline quartz , differing from agate only in that the bands of which it is composed are
..... Click the link for more information. , sardonyx, and jasper jasper, opaque, impure cryptocrystalline quartz , usually red, but also yellow, green, and grayish blue. It is used as a gem. Ribbon jasper has the colors in stripes.
..... Click the link for more information. . Clastic quartzes are sand sand, rock material occurring in the form of loose, rounded or angular grains, varying in size from .06 mm to 2 mm in diameter, the particles being smaller than those of gravel and larger than those of silt or clay .
..... Click the link for more information. and sandstone.

quartz

Second most abundant mineral (after feldspar) in the Earth's crust, present in many rocks. Quartz, which consists of silica, or silicon dioxide (SiO₂), has great economic importance. Many varieties are gemstones, including amethyst, citrine, smoky quartz, and rose quartz. Sandstone, composed mainly of quartz, is an important building stone. Large amounts of quartz sand (or silica sand) are used in the manufacture of glass and ceramics and for molds in metal casting. Crushed quartz is used as an abrasive in sandpaper; silica sand is employed in sandblasting; and sandstone is used whole to make whetstones, millstones, and grindstones. Silica glass (or fused quartz) is used in optics to transmit ultraviolet light. Tubing and various vessels of fused quartz have important laboratory applications, and quartz fibres are employed in extremely sensitive weighing devices.

Quartz

The graphics subsystem in the Mac OS X operating system. It provides two-dimensional drawing and windowing, and its rendering engine is based on the Adobe PDF model. See Mac OS X. See also quartz crystal.

quartz

a colourless mineral often tinted by impurities, found in igneous, sedimentary, and metamorphic rocks. It is used in the manufacture of glass, abrasives, and cement, and also as a gemstone; the violet-purple variety is amethyst, the brown variety is cairngorm, the yellow variety is citrine, and the pink variety is rose quartz. Composition: silicon dioxide. Formula: SiO₂. Crystal structure: hexagonal

quartz (redirected from Star Blue Quartz)

quartz

Quartz

quartz
(redirected from Star Blue Quartz)